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Hepatitis C, Past or Present
2005 Case Definition

Clinical Description

Most hepatitis C virus (HCV)-infected persons are asymptomatic. However, many have chronic liver disease, which can range from mild to severe including cirrhosis and liver cancer.

Laboratory Criteria for Diagnosis

  • Anti-HCV positive (repeat reactive) by enzyme immunoassay (EIA), verified by an additional more specific assay (e.g., recombinant immunoblot assay [RIBA] for anti-HCV or nucleic acid testing for HCV ribonucleic acid [RNA]), OR
  • HCV RIBA positive, OR
  • Nucleic acid test for HCV RNA positive, OR
  • Report of HCV genotype, OR
  • Anti-HCV screening-test-positive with a signal to cut-off ratio predictive of a true positive as determined for the particular assay (e.g., ≥3.8 for the EIA) as determined and posted by CDC.

Case Classification


A case that is anti-HCV positive (repeat reactive) by EIA and has alanine aminotranferase (ALT or SGPT) values above the upper limit of normal, but the anti-HCV EIA result has not been verified by an additional more specific assay or the signal to cutoff ratio is unknown.


A case that is laboratory confirmed and that does not meet the case definition for acute hepatitis C.